The diagnosis of obstructive sleep apnea is frequently made by taking a meticulous history coupled with a high index of suspicion. Snoring and hypersomnolence are clinical features common to individuals with sleep apnea. Since snoring is said to be a "disease of listeners," it is not uncommon that bed partners reported an increased incidence of depression and marital displeasure. It is for this reason that the spouse or bed partner should be interviewed, since the patient may not be aware of any sleeping problems. Physicians should also be alert to complaints of excessive daytime somnolence, because studies have shown that patients with obstructive sleep apnea are at increased risk for automobile crashes. It has been estimated that approx 58,000 motor vehicle accidents involving people with sleep apnea will occur in the US each yr. By proper diagnosis and treatment, the physician is in a unique position to prevent at least some of the automobile accidents that result from falling asleep while driving. Polysomnography is the only definitive way to obtain a diagnosis of sleep apnea. This allows the physician not only to diagnosis the disorder, but also helps in the evaluation of the severity of the syndrome and selection of therapy. An ENT evaluation is also important in ruling out anatomic disorders that can cause upper airway obstruction. Certain factors, such as alcohol and sedative ingestion, may aggravate the condition in a person predisposed to sleep apnea, and subtle changes, such as unexplained hypertension, polycythemia, and cor pulmonale, should lead one to investigate the possibility of sleep apnea as the etiology.